Current transport properties and phase diagram of a Kitaev chain with long-range pairing

We describe a method to probe the quantum phase transition between the short-range topological phase and the long-range topological phase in the superconducting Kitaev chain with long-range pairing, both exhibiting subgap modes localized at the edges. The method relies on the effects of the finite mass of the subgap edge modes in the long-range regime (which survives in the thermodynamic limit) on the single-particle scattering coefficients through the chain connected to two normal leads. Specifically, we show that, when the leads are biased at a voltage V with respect to the superconducting chain, the Fano factor is either zero (in the short-range correlated phase) or 2e (in the long-range correlated phase). As a result, we find that the Fano factor works as a directly measurable quantity to probe the quantum phase transition between the two phases. In addition, we note a remarkable "critical fractionalization effect" in the Fano factor, which is exactly equal to e along the quantum critical line. Finally, we note that a dual implementation of our proposed device makes it suitable as a generator of large-distance entangled two-particle states.Comment: 24 pages, 8 .eps figures Published versio

A Circuit-based Model for the Interpretation of Perfect Metamaterial Absorbers

A popular absorbing structure, often referred to as Perfect Metamaterial Absorber, comprising metallic periodic pattern over a thin low-loss grounded substrate is studied by resorting to an efficient transmission line model. This approach allows the derivation of simple and reliable closed formulas describing the absorption mechanism of the subwavelength structure. The analytic form of the real part of the input impedance is explicitly derived in order to explain why moderate losses of the substrate is sufficient to achieve matching with free space, that is, perfect absorption. The effect of the constituent parameters for tuning the working frequency and tailoring the absorption bandwidth is addressed. It is also shown that the choice of highly capacitive coupled elements allows obtaining the largest possible bandwidth whereas a highly frequency selective design is achieved with low capacitive elements like a cross array. Finally, the angular stability of the absorbing structure is investigated.Comment: Accepted for publication on IEEE Transactions on Antennas and Propagatio

Eigenstates of Operating Quantum Computer: Hypersensitivity to Static Imperfections

We study the properties of eigenstates of an operating quantum computer which simulates the dynamical evolution in the regime of quantum chaos. Even if the quantum algorithm is polynomial in number of qubits $n_q$, it is shown that the ideal eigenstates become mixed and strongly modified by static imperfections above a certain threshold which drops exponentially with $n_q$. Above this threshold the quantum eigenstate entropy grows linearly with $n_q$ but the computation remains reliable during a time scale which is polynomial in the imperfection strength and in $n_q$.Comment: revtex, 4 pages, 4 figure

An Inkjet Printed Chipless RFID Sensor for Wireless Humidity Monitoring

A novel chipless RFID humidity sensor based on a finite Artificial Impedance Surface (AIS) is presented. The unit cell of the AIS is composed of three concentric loops thus obtaining three deep and high Q nulls in the electromagnetic response of the tag. The wireless sensor is fabricated using low-cost inkjet printing technology on a thin sheet of commercial coated paper. The patterned surface is placed on a metal backed cardboard layer. The relative humidity information is encoded in the frequency shift of the resonance peaks. Varying the relative humidity level from 50% to 90%, the frequency shift has proven to be up to 270MHz. The position of the resonance peaks has been correlated to the relative humidity level of the environment on the basis of a high number of measurements performed in a climatic chamber, specifically designed for RF measurements of the sensor. A very low error probability of the proposed sensor is demonstrated when the device is used with a 10% RH humidity level discrimination

Chipless RFID Tag Exploiting Multifrequency Delta-Phase Quantization Encoding

A novel encoding paradigm for chipless RFID tags based on phase quantization is presented. The most distinctive features of this approach are represented by the low requirement on bandwidth and by the encoding scheme. The former is achieved by using only a multi-frequency reading without resorting to ultra-wideband systems whereas the latter relies on linking the information to the quantized difference between the TE and TM phase response of the tag, . The encoding mechanism is described as well as the decoding procedure. The reliability of the illustrated approach is experimentally validated by measurements on fabricated prototypes

SALINITY DISTRIBUTION IN A CHANNELIZED WETLAND AT EMILY AND RICHARDSON PREYER BUCKRIDGE COASTAL RESERVE, TYRRELL COUNTY, NORTH CAROLINA

The Emily and Richardson Preyer Buckridge Coastal Reserve is a low-lying, peatland-dominated freshwater wetland located in the southern Albemarle Estuarine System. The construction of an extensive canal network that facilitated timber harvest and draining of adjacent agricultural lands has altered the water quality and quantity in the Reserve. Brackish conditions observed in the canal network and groundwater system of the Reserve were linked to saltwater intrusion emanating from the Alligator River. Water level, temperature, and specific conductivity data (used as a proxy for salinity) were collected to assess the quantity and quality of the groundwater and surface water system in the Reserve. The driving mechanisms responsible for spatial and temporal variations of salinity in the groundwater and surface water systems were investigated. Seasonal patterns of thermal stratification were observed in the groundwater and surface water systems. Water levels in the Reserve were affected by precipitation events and wind tide events. Specific conductivity levels in the Alligator River and canals were observed to be elevated by wind tides, which are mostly driven by strong southerly winds. The groundwater data reveal that specific conductivity levels are higher in the south of the Reserve than in the north. These observations suggest that the saltwater present in the groundwater and surface water system is emanating from south of the Reserve. The effects of a tropical storm on storm surge and saltwater intrusion in the Reserve were observed to be minimal in this study. Saltwater intrusion is a concern because it may impact the health of vegetation in the Reserve. To prevent further degradation of the environment, restoration and management efforts should focus on the use of water control structures to retard saltwater intrusion during storms and wind tides, and also account for future effects of sea level rise.  M.S

Dynamics of entanglement in quantum computers with imperfections

The dynamics of the pairwise entanglement in a qubit lattice in the presence of static imperfections exhibits different regimes. We show that there is a transition from a perturbative region, where the entanglement is stable against imperfections, to the ergodic regime, in which a pair of qubits becomes entangled with the rest of the lattice and the pairwise entanglement drops to zero. The transition is almost independent of the size of the quantum computer. We consider both the case of an initial maximally entangled and separable state. In this last case there is a broad crossover region in which the computer imperfections can be used to create a significant amount of pairwise entanglement.Comment: 4 pages, 4 figure

Multi-frequency polarizarition converter with enhanced angular robustness

This paper presents a multi-frequency polarization converter for linear polarized waves. The reflection-based polarization converter is realized with a periodic surface. The unit cell comprises loaded dipoles printed on a metallic backed Teflon substrate 1.52mm thick. The unit cell topology results to be robust to the variation of the azimuthal incident angle. For this reason, the proposed device is particularly suitable for applications in which the direction of arrival of electromagnetic w ave is unknown

Lipid Metabolism and Cardiovascular Risk in HIV-1 Infection and HAART: Present and Future Problems

Many infections favor or are directly implicated with lipid metabolism perturbations and/or increased risk of coronary heart disease (CHD). HIV itself has been shown to increase lipogenesis in the liver and to alter the lipid profile, while the presence of unsafe habits, addiction, comorbidities, and AIDS-related diseases increases substantially the risk of cardiovascular disease (CVD) in the HIV-infected population. Antiretroviral therapy reduces such stimuli but many drugs have intrinsic toxicity profiles impacting on metabolism or potential direct cardiotoxicity. In a moment when the main guidelines of HIV therapy are predating the point when to start treating, we mean to highlight the contribution of HIV-1 to lipid alteration and inflammation, the impact of antiretroviral therapy, the decisions on what drugs to use to reduce the probability of having a cardiovascular event, the increasing use of statins and fibrates in HIV-1 infected subjects, and finally the switch strategies, that balance effectiveness and toxicity to move the decision to change HIV drugs. Early treatment might reduce the negative effect of HIV on overall cardiovascular risk but may also evidence the impact of drugs, and the final balance (reduction or increase in CHD and lipid abnormalities) is not known up to date